The first frost of autumn is shown to activate the timing of flowering, research at the John Innes Centre has found.
It is known that, for some varieties, exposure to an extended period of cold ‘vernalization’ is a preparation for flowering in spring.
The gene FLC creates a brake on flowering and its action is controlled by a molecule called COOLAIR. Researchers compared natural types of Arabidopsis grown in different climates (Norfolk, south Sweden, subarctic north Sweden) and measured the levels of COOLAIR.
COOLAIR levels varied among different accessions and different locations. However, the researchers spotted that when temperature first dropped below freezing there was a peak in COOLAIR.
Dr Yusheng Zhao, co-first author of the study, said: “Our study shows the first seasonal frost serves as an important indicator in autumn for winter arrival and helps to explain how plants sense environmental signals to align flowering with spring.”
To confirm this boosting of COOLAIR after freezing the researchers did experiments in temperature-controlled chambers which simulated the temperature changes seen in natural conditions.
They found COOLAIR expression levels rose within an hour of freezing and peaked about eight hours afterwards. There was a small reduction in FLC levels immediately after freezing too, reflecting the relationship between the two key molecular components.
Next, they found a mutant Arabidopsis which produces higher levels of COOLAIR all the time, even when it is not cold, and low levels of FLC. When they edited the gene to switch off COOLAIR they found that FLC was no longer suppressed, providing further evidence of this elegant molecular mechanism.
The study offers insight into the plasticity in the molecular process of how plants sense temperatures, which may help plants adapt to different climates, and could be translatable to improving crops at a time of climate change.
The study: Natural temperature fluctuations promote COOLAIR regulation of FLC appears in Genes & Development.